The invention relates to a method of controlling a seat belt device, which is connected to a seat belt, of a vehicle with a collision detection unit that includes sensor units for detecting an imminent collision with a vehicle-external collision object. The invention also relates to a device for performing the method according to the invention.
U.S. Pat. No. 6,085,151 B describes a generic method, with which an object that is expected to collide with a vehicle can be detected with a predictive collision detection unit of the vehicle collision of before an actual crash. The time until impact with the collision object is estimated, the type of the accident is identified and the severity of the accident is estimated and used, for example, to control a belt tensioner and to thereby increase the safety of vehicle occupants. However, it is not described how the severity of the accident is determined.
Furthermore, DE 103 45 726 A1 discloses a restraint system for restraining an occupant in a motor vehicle and a method for dynamically controlling such a restraint system. In this known method, the vehicle situation is determined with a situation detection device and the parameter data of the occupants are determined with a parameter detection device, wherein the force of the seatbelt tensioner is dynamically controlled commensurate with the situation by a control unit and by taking into account the vehicle situation and the parameters of the occupants. The force of the belt tensioner applied to the seatbelt can thus be actively controlled before or during an accident and can thus be adapted to the current vehicle situation and occupants' situation, for example, the occupants' position and weight. Furthermore, when a high hazard potential is detected, the force of the belt tensioner can be increased and the force of the belt tensioner can subsequently be reduced again when the danger has abated and the risk potential has diminished. The situation detection device of this conventional restraint system is configured as an environment sensor system for monitoring the environment of the vehicle, for example relevant accident objects. Using these environment sensors, the impact velocity, the impact time, the impact angle, the impact location and the impact overlap can be determined. In addition, the situation detection device can also be configured as an accident sensor system for detecting the accident acceleration, the accident severity, the accident type, or the like. These data can then be taken into account in the dynamic control of the force of the belt tensioner.
The parameter detection device for determining the parameter of the occupants is in this conventional restraint system configured as an occupant sensor system for determining the occupants' position, the occupants' weight, the occupants' size, the seat position, the seat belt extension length or the like. Furthermore, the hazard potential is determined from the data captured, for example, in a pre-crash phase, and the survival space between the occupant and for example the air bag is determined in a crash phase, and the force of the belt tensioner is dynamically controllable so that the entire available survival space of the occupant is utilized. The survival space is here the space between the occupant and a possible object, for example an airbag, a steering wheel or a glove compartment, which the occupant may strike. The publication DE 03 45 726 A1 does not disclose how the risk potential is determined in the pre-crash phase.